14. Clouds

When the moist air ascends, it expands, loses temperature, becomes cool, and gets saturated. With further decrease in temperature beyond the dew point, condensation of the moisture takes place high up in the air and it results in the formation of clouds. Clouds are droplets of water or tiny ice crystals which collect around the dust particles present in the atmosphere. The water droplets and tiny ice crystals that remain suspended in the air can be disturbed by the slightest movement of the air. All forms of precipitation occur from the clouds. It should be noted that not all clouds yield precipitation but no precipitation is possible without the

clouds. The clouds play a major role in the heat budget of the Earth and the atmosphere, as they reflect, absorb and diffuse some part of the incoming solar radiation. They also absorb a part of the outgoing terrestrial radiation and then re-radiate it back to the Earth’s surface. Whenever there are clouds in the sky, some sort of precipitation always occurs, although we do not feel it on the Earth. Much of it is re-evaporated during its descent through the warm and dry air. Clouds are more common on the windward slopes of the mountains than on the leeward slopes. Clouds are more frequent during the cyclones than during the anticyclones.